Adjustments; Set Gas Input Rate - Carrier WeatherMaker 8000 Installation, Start-Up, And Operating Instructions Manual

f. Blower motor operates on heating speed for 10 sec, then
stops.
g. Inducer motor stops.
3. To operate furnace, follow procedures on operating instruction
label attached to furnace.
4. With furnace operating, set thermostat below room tempera-
ture and observe that furnace goes off. Set thermostat above
room temperature and observe that furnace restarts.

ADJUSTMENTS

1. Set gas input rate

Furnace gas input rate on rating plate is for installations at
altitudes up to 2000 ft. Furnace input rate must be within ±2
percent of input on furnace rating plate.
a. Determine natural gas orifice size and manifold pressure
for correct input.
(1.) Obtain average yearly heat value (at installed altitude)
from local gas supplier.
(2.) Obtain average yearly specific gravity from local gas
supplier.
(3.) Verify furnace model. Table 7 can only be used for
model 58ZAV Furnaces.
(4.) Find installation altitude in Table 7.
NOTE: For Canada altitudes of 2000 to 4500 ft, use U.S.A.
altitudes of 2001 to 3000 ft in Table 7.
(5.) Find closest natural gas heat value and specific gravity
in Table 7.
(6.) Follow heat value and specific gravity lines to point of
intersection to find orifice size and manifold pressure
settings for proper operation .
EXAMPLE: (0—2000 ft altitude)
Heating value = 1050 Btu/cu ft
Specific gravity = 0.62
Therefore: Orifice No. 43*
Manifold pressure 3.6-in. wc
* Furnace is shipped with No. 43 orifices. In this example
all main burner orifices are the correct size and do not need
to be changed to obtain proper input rate.
(7.) Check and verify burner orifice size in furnace.
NEVER ASSUME ORIFICE SIZE. ALWAYS
CHECK AND VERIFY.
b. Adjust manifold pressure to obtain input rate.
(1.) Remove regulator adjustment seal cap. (See Fig. 17.)
(2.) Turn adjusting screw, counterclockwise (out) to de-
crease manifold pressure or clockwise (in) to increase
manifold pressure.
NOTE: This furnace has been approved for a manifold pressure
of 3.2-in. wc to 3.8-in. wc when installed at altitudes up to 2000 ft.
For altitudes above 2000 ft, the manifold pressure can be adjusted
from 2.0-in. wc to 3.8-in. wc.
DO NOT bottom out gas valve regulator adjusting screw.
This can result in unregulated manifold pressure and result in
excess overfire and heat exchanger failures.
NOTE: If orifice hole appears damaged or it is suspected to have
been redrilled, check orifice hole with a numbered drill bit of
correct size. Never redrill an orifice. A burr-free and squarely
aligned orifice hole is essential for proper flame characteristics.
(3.) After correct manifold pressure is obtained, replace
gas valve regulator adjustment screw cap and verify
adjusted gas input rate using method outlined in item
c.
(4.) Burner flame should be clear blue, almost transparent.
(See Fig. 17.)
c. Verify natural gas input rate by clocking gas meter.
NOTE: High-Altitude Adjustment
United States
At installation altitudes above 2000 ft, this furnace has been
approved for a 4% derate for each 1000 ft above sea level. See
Table 8 for derate multiplier factor.
Table 8—Altitude Derate Multiplier for U.S.A.
ALTITUDE
(FT)
0—2000
2001—3000
3001—4000
4001—5000
5001—6000
6001—7000
7001—8000
8001—9000
9001—10,000
* Derate multiplier factor is based on midpoint altitude for altitude range.
EXAMPLE:
92,000 Btuh input furnace installed at 4300 ft.
Furnace Input
Rate at X
Sea Level
92,000
Canada
At installation altitudes from 2000 to 4500 ft, this furnace must be
derated 10% by an authorized Gas Conversion Station. To deter-
mine correct input rate for altitude, see example above and use
0.90 as derate multiplier factor.
a. Turn off all other gas appliances and pilots.
b. Start furnace and let operate for 3 minutes.
c. Measure time (in sec) for gas meter test dial to complete 1
revolution.
d. Refer to Table 9 for cu ft of gas per hr.
e. Multiply gas rate (cu ft/hr) X heating value (Btu/cu ft)
using natural gas heating value from local gas
utility/supplier.
EXAMPLE: (0—2000 ft altitude)
Btu heating input = Btu/cu ft X cu ft/hr
Heating value of gas = 1050 Btu/cu ft
Time for 1 revolution of 2-cu ft dial = 82 sec
Gas rate = 88 cu ft/hr (from Table 9)
Btu heating input = 88 X 1050 = 92,400 Btuh
In this example, the orifice size and manifold pressure
adjustment is within ±2 percent of the furnace input rate.
14
% OF DERATE MULTIPLIER
DERATE FACTOR FOR U.S.A*
0 1.00
8—12 0.90
12—16 0.86
16—20 0.82
20—24 0.78
24—28 0.74
28—32 0.70
32—36 0.66
36—40 0.62
Derate Furnace Input Rate
Multiplier = at Installation
Factor Altitude
0.82 75,440